<?php

$str = 'Wörks wíth all ストリングズ';

$numbers = array();
foreach (str_split($str) as $chr) {
    $numbers[] = sprintf('%03d', ord($chr));
}
$numbers = join($numbers);

echo $numbers, PHP_EOL;

echo join(array_map('chr', str_split($numbers, 3)));

087195182114107115032119195173116104032097108108032227130185227131136227131170227131179227130176227130186
Wörks wíth all ストリングズ